Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Cash paid for federal and state taxes	$ 381	$ 2,582
Non-cash transactions:
Change in accounts payable related to property and equipment additions	0	382
Property and equipment acquired under capital leases	$ 1,808	$ 0